The present invention relates to novel esters of phosphorous acid and phosphoric acid and to a novel method for their production. More particularly, the novel compounds are (halo)(hydroxy)-substituted phosphites and phosphorates and (halo)(hydroxyl)alkyl ester derivatives of phosphorus compounds. The compounds are particularly useful, respectively, as flame retardant additives and reactants in polyurethanes.
In U.S. Pat. No. 3,939,227, the reaction between a halide of an alkyl phosphonic acid and a hydroxy-terminated epoxy was reported. Specifically, the reference disclosed the reaction of glycidol with chloromethyl phosphonic dichloride. The reported product was a diol of the formula ##STR1## where R was chloromethyl; X was chloro; and a was 1. The compound was found to be a highly viscous material. No further characterizing data was supplied.
The method illustrated by the above reference has proven difficult in practice due to the competing reactions between hydroxyl, instead of the suggested epoxy moieties, with the active phosphorus reactant sites resulting in impure product and high molecular weight oligomers as indicated by the viscous nature of the reported product. It is, for example, well-known that phosphonic chlorides react only with great difficulty with epoxy groups unless a catalyst is employed, cf. U.S. Pat. Nos. 1,936,985; 2,160,978; 3,010,980; etc. Accordingly in U.S. Pat. No. 3,939,227, low temperatures were employed along with slow addition of the phosphorus compound to a dilute solution of the epoxide in order to limit, if possible, competing reactions of the hydroxyl moiety. This process is not commercially acceptable and, as previously explained, was not entirely successful in U.S. Pat. No. 3,939,227 in preventing contaminating reaction products as indicated by the highly viscous nature of the reported product. The highly viscous reaction product is unsuitable in many applications requiring a polyhydroxyl-containing compound having low hydroxyl equivalent weight.
Furthermore, the reaction technique of U.S. Pat. No. 3,939,227 is not amenable for use with more reactive phosphorus compounds, such as POCl.sub.3, PCl.sub.3, or PCl.sub.5. The competing reaction of hydroxyl moieties with these more reactive phosphorus compounds readily forms undesirable reaction products.
Accordingly, it is an object of the present invention to provide a process whereby highly pure (halo)(hydroxyl)alkyl phosphites and phosphorates may be prepared expeditiously and in high yield under commercially acceptable reaction conditions and times.
It is a further object of the present invention to produce highly pure (halo)(hydroxyl)alkyl ester derivatives of phosphorus compounds of low viscosity, which are suitable for use as intermediates in producing ignition resistant polyurethanes by reaction with a diisocyanate-containing compound. In this role the derivatives are therefore reactants in the polyurethane system. Preferably the (halo)(hydroxy)-substituted esters have a viscosity less than 500,000 centipoise at ambient temperatures in order that the compound be tractable and capable of use without employing a solvent.
Finally, it is an object of the present invention to produce highly pure (halo)(hydroxyl)alkyl ester derivatives of phosphorus compounds of low viscosity which are suitable for use as additives in polyurethanes. These additives impart ignition resistance.
These and other objects will be more fully illustrated with reference to the description of the preferred embodiments below.
Accordingly, the instant invention provides a substituted 2-halopropoxy phosphorus-containing compound selected from the group consisting of: ##STR2## wherein: X is halo-, preferably chloro- or bromo-:
R is hydroxy, halo, or a moiety having up to 10 carbons selected from alkyl, aryl, haloalkyl, haloaryl, alkoxy, alkoxyalkyl, aryloxyalkyl, haloalkoxy, and haloalkoxyalkyl; PA0 R' is a divalent moiety having up to 10 carbons selected from alkylene, arylene, alkyl- and aryl-substituted derivatives thereof, and (OCH.sub.2 CHR").sub.x wherein R" is hydrogen, methyl, ethyl or halomethyl, and x is 1, 2 or 3; PA0 at least one Q is hydrogen and any remaining Q is independently hydrogen or a dealkylatable alkyl moiety; PA0 m is zero or 1; and PA0 n is a number greater than or equal to zero and less than 3 that indicates the number of equivalents of specified moiety per mole of the named compounds; PA0 the compound having a viscosity at 25.degree. C. as measured by a Brookfield viscosity meter of less than 500,000 centipoise. PA0 R'" is a moiety having up to 10 carbons selected from the group consisting of alkyl, aryl, haloalkyl, haloaryl, alkoxy, alkoxyalkyl, aryloxyalkyl, haloalkoxy and haloalkoxyalkyl. PA0 ethylene oxide PA0 propylene oxide PA0 epihalohydrin PA0 trihalobutylene oxide PA0 styrene oxide PA0 1,2-epoxy-3-phenoxypropane PA0 1,2-epoxy-3-isopropoxypropane PA0 1,2-epoxy-3-halophenoxypropane PA0 etc.
The instant invention also provides compounds of the above general formulas wherein Q is a dealkylatable alkyl moiety only.
The compounds are formed by reaction of an alkyl glycidyl ether capable of producing an ester reaction product which may subsequently be dealkylated to produce a hydroxyl moiety with at least one reactive phosphorus-containing compound of the formula: ##STR3## wherein: X and n are as previously defined; and
Optionally, other epoxide-containing compounds may be reacted with the reactive phosphorus-containing compound. Such additional epoxide-containing compounds may be reacted before, after or simultaneously with the previously mentioned alkyl glycidyl ethers.
A further option according to the invention is to react a hydroxyl-containing compound with the above formed reaction product of the phosphorus-containing reactant and a stoichiometrically insufficient amount of the epoxy compounds. Because of the previously described inability to mix epoxy- and hydroxyl-containing reactants, the above hydroxyl-containing compounds are reacted either before or after the reaction of the epoxy-containing compounds.
Suitable alkyl glycidyl ethers are compounds of the formula ##STR4## where R' and m are as previously defined; and Q is an alkyl moiety such as tertiary butyl or tertiary amyl that may be easily removed under acid conditions to produce a hydroxyl moiety. Preferably Q is tertiary butyl and a preferred alkyl glycidyl ether is tertiary butyl glycidyl ether (TBGE).